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Earth Bag Building Method
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The Cal-Earth bags enable you to build a home mostly from the dirt under your feet, mixed with ~10% concrete and 10% water, with a great deal of artistic freedom in wall shape; using arch construction, eliminating the need for a separate roof. Makes home building far more affordable and renewable while giving you thermal mass to save on heating/cooling costs.
 A view from inside an earth bag home whose walls/ceiling have not yet been grouted and finished. Courtesy http://CalEarth.org |
The Earth Bag or Superadobe building method basically entails long bags of dirt from the building site laid in layers, forming arched structures for strength, so that the stacks serve as both the walls and roof of the structure. The wetted earth can either be compacted by pounding (rammed earth) to make it hard, or ~10% cement can be added with ~10% water so that the mixture hardens, with the bag providing the form. Cal-Earth sells 1-mile long lengths of both 22- and 18-inch wide bagging for a few thousand dollars. The bagging is cut to length, and then sewed shut with twine.
A good analogy of this construction method is the clay pot one might build in elementary school using rolls of clay, shaping it into a beehive type configuration, though there are a lot of other shapes that can be sturdy. Another common shape is a "barrel vault" or half pipe. The rolls of clay are 22 inches wide and 6 inches high.
The Superadobe technology (sandbag tubes and barbed wire) was designed and developed by architect Nader Khalili and Cal-Earth Institute, and engineered by P.J. Vittore. According to Cal-Earth, "Superadobe is a patented system (U.S. patent #5,934,027) freely put at the service of humanity and the environment. Licensing is required for commercial use."
If cement is used, the bags with earth harden in about four hours. Within a week, it would be advised to cut the channels for running electrical wire or conduit.
With the thick thermal mass walls (22-inches of earth), they help reduce heating and cooling bills. Also, their arch-based shape makes them very strong, exceeding the strength of most other structure types, making them ideal for seismic-prone areas, while also being more affordable (~$60/ft2) than most building types. Also the strength contributes to longevity. As the different rows are added to each other, they "become as one complete piece." Proponents say these buildings could last 500 to 1000 years. "They're monuments." The early models were run through third party testing by an engineering firm who placed 2000 tons of lateral pressure on top and did not detect a single failure.
They are usually finished off with grouting between rows of bags. Some kind of waterproofing needs to be put on the exterior, such as a rubberized coating. The final finish can be stucco, both on the inside and outside. The concept is also modular, so if the home needs to be expanded, another unit can be added on to it.
As of 2007, there were around 3,000 Earth Bag homes built around the world, ranging from Siberia to Costa Rica. Permits have been issued in U.S. states including: AZ, HI, CA, UT, NV, WA, KY; as well as in BC in Canada. Unless the code requires otherwise, the first row of bags can be placed right on the ground, without a footer.
They have been used in disaster relief, providing a rapid way to build a shelter of 120 - 200 square feet.
Speaking of disasters, the barbed wire rows in the walls, and the chicken wire mesh used in adhering the stucco, could conceivably serve as a partial Farrady cage for protection from an EMP incident.
If water catchment is desired, a gutter can be built into the roof. A greenhouse can be built exterior to the south walls, with its roof butting into the structure via angle iron.
See our page on this at http://peswiki.com/index.php/Directory:Earth_Bag_Building_Method
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